New isoflavonoid glycosides and related constituents from astragali radix ( Astragalus membranaceus ) and their inhibitory activity on nitric oxide production

Twenty-four secondary metabolites, including 16 isoflavonoids, 7 astragalasides, and 1 benzoquinone, have been isolated from the roots of Astragalus membranaceus (Astragali radix). Among these isolated isoflavonoids, (-)-methylinissolin 3-O-β-d-(6'-acetyl)-glucoside (1), (-)-methylinissolin 3-O-β-d-{6'-[(E)-but-2-enoyl]}-glucoside (2), and calycosin 7-O-β-d-(6'-acetyl)-glucoside (3) have been identified as new compounds on the basis of spectroscopic analysis; (-)-methylinissolin 3-O-β-d-glucoside (4) was isolated from the natural products for the first time. The nitric oxide (NO) production inhibitory activity of the major compounds has been assessed in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. To identify A. membranaceus, a fingerprint method was developed by using a high-performance liquid chromatography-evaporative light scattering detector (HPLC-ELSD) method. Furthermore, characteristic peaks for the 11 major compounds in the chromatogram were unambiguously confirmed.     

影响茄子外观品质的原因及对策

本文从裂茄、僵茄等影响茄子外观品质的成因及相应对策等方面进行了综述,供中国茄子育种科研工作者参考,并期望对提高国内茄子遗传研究与育种利用水平有所帮助。     

超声复合酸处理促进花生分离蛋白的亚基解离

为了改善蛋白质的功能特性,该研究分析了超声复合酸处理对花生分离蛋白的溶解性、紫外光谱、荧光光谱、二级结构及纳米结构等的影响,并探讨不同处理条件下蛋白聚集体结构变化的机理。结果表明,超声作用可以明显促进花生分离蛋白的不溶性聚集体向可溶性聚集体转变,单独超声及超声复合酸处理使其溶解度相对于对照分别增加了12.9%和15.3%（P<0.05）;电泳、紫外和荧光光谱表明,超声和酸作用均有助于亚基解离及蛋白质结构展开,从而促进更多的酪氨酸、色氨酸和苯丙氨酸等疏水性基团暴露;圆二色谱分析显示,与对照相比,在超声复合酸处理使花生分离蛋白的a-螺旋增加21.9%,β-折叠减少3.6%,无规则卷曲增加1.8%（P<0.05）;纳米结构表明,超声复合酸处理最大程度地降低了花生分离蛋白的颗粒大小。该研究证实,在酸性条件下进行超声处理,能显著促进花生分离蛋白的亚基解离和结构展开。该研究为后期蛋白亚基重新相互作用形成不同功能的改性蛋白提供参考。     

Culture-dependent and culture-independent microbial investigation of pine litters and soil in subtropical Australia

Background, aim, and scope  Forest plantations, widely grown for wood production, involve the selective promotion of single-tree species or replacement of natural species by exotic tree species. Slash pine (Pinus elliottii) has been chosen for reforestation of infertile sandy soils in southeast Queensland, Australia. These exotic pine plantations minimize soil and water losses and are important scientific study sites. The soil environment of these plantations, though devoid of sufficient nutrients, organic carbon and other factors, harbors innumerable bacteria that may play a crucial role in maintaining soil quality and ecosystem functions. These soil microorganisms also have the potential for use as sensitive biological indicators to reflect environmental changes. It is therefore essential to understand the interrelationships among bacterial communities and their environment by assessing their structural and functional diversity and their responses to disturbances. The main aim of our investigation was to determine the diversity of bacterial communities in forest litters and soil during the forest leaf litter decomposition using culture-dependent and culture-independent techniques. Materials and methods  A 25-cm (diameter) × 40-cm core sample was collected and fractionated into three subsamples designated E1 (L leaf litter layer), E2 (F leaf litter layer), and E5 (0–10 cm soil layer). Both culture-dependent and culture-independent methods were applied in this study. In the culture-independent study, a strategy of whole-community DNA extraction, polymerase chain reaction (PCR) amplification followed by cloning and 16S rDNA sequence analysis was used; for culture-dependent study, the strategy included sample plating and bacteria isolating, DNA extraction, PCR amplification, and 16S rDNA sequence analysis. The diversity similarities between two bacterial communities and two methods are quantified using Jensen–Shannon divergence. Results  From culture-dependent study, 336 colonies in total were isolated and grouped from the three subsamples, and the 16S rRNA sequence analysis from a representative isolate from each morphogroup (21 isolates) indicated that they belonged to the phyla Actinobacteria, Firmicutes, and Proteobacteria. Culture-independent assessment based on 16S rRNA gene library comprising 194 clones revealed that members of the phylum Actinobacteria were absent in the culture-independent studies. Clones in libraries from E1 consisted exclusively of members of the Firmicutes. The majority of clones from E2 were related to Firmicutes (79%) and Proteobacteria (21%). Clones derived from E5 were mostly affiliated with Acidobacterium (42%), followed by unclassified bacteria (27%), Verrucomicrobiales (12%), Proteobacteria (11%), and Planctomycetes (8%). Discussion  This study showed that bacterial culturabilities in different fractions of leaf litters were similar, and both of them were higher than the bacterial culturability in the soil. Unculturable bacterial diversity in the soil, however, was much higher than the leaf litter bacterial diversity. The bacterial diversity on the top layer of leaf litters was slightly less than that on the bottom layer of leaf litters. This might indicate that forest soils are a more complex environment than leaf litters are and also that they might inhabit more unculturable microorganisms in the forest soils, which would need to be further investigated. The leaf litter layer samples also demonstrate the significant difference between the bacterial community diversity discovered by these two methods in this study. The information provided by assessing the different fractions of leaf litters and forest soil has improved our understanding of the bacterial community distributions within the forest soil and the above-leaf litters in an exotic pine plantation of subtropical Australia. Conclusions  This study represents the first attempt to examine the bacterial community in the different fractions of forest leaf litters and soil in subtropical Australia. The data from this study show that the 16S rDNA clone libraries provided more comprehensive phylogenetic diversity in the soil and leaf litter samples than the culture collections provided, and both the culture-dependent and culture-independent studies revealed that the bacterial diversity present in the leaf litters was very different to that present in the soil. The comparative analysis of bacterial communities in different fractions of leaf litters and soil samples has also provided important baseline information about the bacterial diversity and composition in the exotic pine forest plantations. Recommendations and perspectives  The experimental data provided important information on the bacterial diversity in forest leaf litter and soil samples, though additional surveys and comparisons at different locations would be needed to further characterize. In addition, combined methods that can provide different parts of information on bacterial diversity are encouraged to be used in bacterial community study. The established libraries of diverse 16S rRNA gene fragments from slash pine leaf litters and forest soil can be used to construct specific DNA primers and probes to target bacterial groups of interest. It may then be possible to study the ecology of these bacterial communities and the role of specific bacterial groups that contribute to the many interesting properties of these environments.     

基于光谱技术的水稻叶片氮素测定仪的开发

在理论分析的基础上设计开发了一套基于光谱技术的水稻叶片SPAD值和氮素测定仪。该测定仪主要包括光路部分、调理电路和控制与数据采集器等。光路部分包括光源、检测点以及光电传感器等元器件,主要作用是：控制光源的亮灭、收集透过叶片光线、将光信号转换为电信号;调理电路主要将所得微弱电信号进行电流电压转换以及放大到合适的幅度;控制与数据采集器包括AD转换电路,液晶显示电路和SD卡存储电路。对该测定仪的性能进行了测试,试验分为两步：先建立AD采样电压信号与SPAD值之间的模型,然后建立SPAD值与氮素之间的模型。经过大量的试验测得：传感器转换的电压信号与SPAD值之间存在很高的相关性（R2 =0.956）,SPAD值与氮含量建立的模型的决定系数为R2 =0.802,结合以上两种模型得到该仪器的氮素模型的决定系数为R2 =0.766。该仪器适合用于田间水稻叶片氮素含量的快速测量。     

蓝粒小麦4Ag染色体的显微分离与鉴定

本研究采用显微分离技术从蓝粒小麦(Triticum aestivum L.(2n=6x=42)×Thinopyrum ponticum Liu &Wang(2n=10x=70))根尖细胞中期分裂相中分离出具有4Ag染色体形态特征的单条染色体,对分离后的细胞进行原位杂交(FISH),结果显示细胞中所剩的和显微分离到的单条染色体均为4Ag染色体.利用Sau3A接头介导的PCR方法对分离出的单条4Ag染色体进行体外扩增,扩增的DNA片段大小约为200～2 000 bp,主要集中在250～750 bp之间.以DIG-dUTP标记的蓝粒基因组DNA为探针,与该扩增产物进行Southern杂交,结果表明显微分离出的染色体得到了有效的扩增.利用该分离染色体的PCR扩增产物为探针,对蓝粒小麦进行原位杂交,证明显微分离的染色体体外扩增片段确实来源于4Ag染色体.本研究拓宽了染色体显微分离的范围,为构建4Ag染色体文库和克隆位于该染色体上的重要农艺性状基因提供了新途径.     

采后硅酸钠处理对贮藏期兰州“大接杏”果实品质和挥发性风味物质的影响

本文以兰州“大接杏”（Armeniaca vulgaris Lam. cv. Lanzhou Dajie）为试材,使用硅酸钠（10 mM）化学诱抗处理,以探讨其对杏果实品质,特别是挥发性风味物质的影响。结果表明,硅酸钠处理可延缓果实硬度、可滴定酸、可溶性固形物（SSC）和Vc含量的下降,但对果实总糖含量的影响不显著。采用固相微萃取（SPME）结合气相色谱质谱联用（GC-MS）的方法分离鉴定了“大接杏”果实的香气成份,共分离鉴定出超过100多种挥发性成份。硅酸钠处理样挥发性物质的释放总量低于对照,同时处理后的杏果还表现出醛类物质、萜类物质和β-紫罗兰酮的释放增大和脂类物质的释放减少的现象。     

冷激黄瓜贮藏品质及冷激过程传热特性分析

为研究冷激处理对黄瓜保鲜效果的影响及冷激过程中黄瓜内部组织传热机理,建立了黄瓜冷激过程的传热数学模型,并以0℃的冰水混合物为冷激介质,对处理时间分别为20、40、60 min黄瓜的保鲜效果进行了对比试验研究。结果表明,黄瓜保鲜效果差异不仅与冷激处理时组织的最低温度有关,还与最低温度持续的时间有关。冷激处理40 min能够有效抑制黄瓜硬度、可溶性固形物含量的下降,减缓失重率的上升,保持较高的过氧化物酶活性。所建的传热模型能够准确预测冷激处理过程中黄瓜不同深度位置处的组织温度变化。冷激传热模型及相关结论可为黄瓜采后冷激处理工艺提供理论及实践指导。     

兰州百合真空干燥图形组态系统研制

为了实现各类生产数据的良性管理和干燥全过程的高效监控等质量保证措施,引入图形组态理念,从对干燥现场的分类抽象和对各类过程数据的动态重构入手,研制了基于Visual Graph图形开发工具和SQL 2005数据库的面向兰州百合真空干燥的图形组态系统,并应用于工程实践。同时探讨了图形组态系统网络化编辑和控制的实现策略。实际应用表明：兰州百合真空干燥图形组态系统能够增强多源异构数据的协调管理,实现干燥过程的高效监控,满足用户对操作界面直观简便的需求。